Rolling-element clutch assembly

ABSTRACT

A rolling-element clutch assembly including a first race member, a second race member and a plurality of rolling elements. The first race member defines a first race surface having a first ratchet surface portion. The second race member defines a second race surface having a second ratchet surface portion. The first race surface and the second race surface define a raceway therebetween. A plurality of rolling elements are disposed in the raceway. The rolling elements provide rolling support between the first race member and the second race member when the first race member moves in a first direction relative to the second race member. At least one of the plurality of rolling elements engages the first and second ratchet surface portions when the first race member moves in a second direction relative to the second race member. The engagement of the rolling element with the first and second ratchet surfaces impedes relative motion between the first race member and the second race member, thereby providing load transmission capability. The profile of each sawtooth incline may be formed from one or more flat planes. A rolling element separator may be provided, the separator allowing the rolling elements to freely roll when the first race member moves in a first direction relative to the second race member and to freely pivot into engagement with or disengagement from the ratchet surfaces when the first race member moves in a second direction relative to the second race member.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a division of U.S. application Ser. No. 09/206,618 filed on Dec.7, 1998.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention pertains to the field of clutching mechanisms,and, in particular, to a rolling-element clutch.

2. Description of the Related Art

A freewheel clutch is a device that will drive a rotating load in onedirection, but will allow it to freewheel or spin at any speed in theother direction. There is a need to make a more compact and ruggedfreewheel clutch. All current designs need separate devices to supportthe rotating load on the shaft and to have the shaft drive this load.Current techniques are called ratchet and pawl, wrap spring, sprag,roller clutch, ball clutch, tilting plate, and so forth. Each of theserelated art devices needs the addition of some bearing device to supportthe driven load when it is in the freewheel mode.

The typical related art is represented by a one-way clutch bearinghaving an outer race with an annular inner surface, an inner race withan annular outer surface corresponding to and concentric with the innersurface, and rolling members disposed in an annular space formed betweenthe inner surface and the outer surface, whereby relative rotation ofthe inner and outer races in one direction is prevented by displacementof the rolling members in the space and a torque is transmitted. Aholding means for holding the rolling members is provided at adisplacement position whereat the rolling members transmit apredetermined transmission torque, and a means is provided fordecreasing a wedge angle at a position before the rolling members arriveat the displacement position.

U.S. Pat. No. 5,573,094, which is assigned in common with the presentinvention and incorporated herein by reference, discloses a combinationbearing/freewheel clutch that is provided with an inner race memberdefining an inner race surface, an outer race member defining an outerrace surface concentric with the inner race member, and a racewaybetween the inner and outer races. The inner and outer race members eachhave a series of short radially oriented sawtooth inclines in theirrespective inner and outer race surfaces at right angles to the raceway.A plurality of modified ball bearings, for instance ball bearings haveflattened poles, are disposed in the raceway between the inner and outerrace members, such that the modified ball bearings serve to preventrelative rotation of the inner and outer race members in one direction,and to transmit a torque between the inner and outer races.

Although the invention of U.S. Pat. No. 5,573,094 represents asignificant development in the art of combination bearing/freewheelclutches, there is need for improvement to provide a rolling-elementclutch that is stronger, lighter, more reliable, easier to manufacture,and easier to assemble.

SUMMARY OF THE INVENTION

The advantages and purpose of the invention will be set forth in part inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. Theadvantages and purpose of the invention will be realized and attained bymeans of the elements and combinations particularly pointed out in theappended claims.

To attain the advantages and in accordance with the purpose of theinvention, as embodied and broadly described herein, the rolling-elementclutch assembly of the invention, in a first aspect, includes a firstrace member, a second race member and a plurality of rolling elements.The first race member defines a first race surface having a firstratchet surface portion. The second race member defines a second racesurface having a second ratchet surface portion. The first race surfaceand the second race surface define a raceway therebetween. A pluralityof rolling elements are disposed in the raceway. The rolling elementsprovide rolling support between the first race member and the secondrace member when the first race member moves in a first directionrelative to the second race member. At least one of the plurality ofrolling elements engages the first and second ratchet surface portionswhen the first race member moves in a second direction relative to thesecond race member. The engagement of the rolling element with the firstand second ratchet surfaces impedes relative motion between the firstrace member and the second race member, thereby providing loadtransmission capability. The first ratchet surface portion including aplurality of inclines extending along the first race surface in thefirst direction, each incline embedded in the first race surface andhaving a profile adapted for engaging one of the plurality of rollingelements, the profile of each incline being formed from one or more flatplanes.

In a second aspect, the rolling-element clutch assembly of the inventionincludes a first race member, a second race member and a plurality ofrolling elements. The first race member defines a first race surfacehaving a first ratchet surface portion. The second race member defines asecond race surface having a second ratchet surface portion, and thefirst race surface and the second race surface define a racewaytherebetween. The plurality of rolling elements are disposed in theraceway and provide rolling support between the first race member andthe second race member when the first race member moves in a firstdirection relative to the second race member. At least one of theplurality of rolling elements engage the first and second ratchetsurface portions when the first race member moves in a second directionrelative to the second race member, thereby impeding relative motionbetween the first race member and the second race member and providingload transmission capability. The first race member defines a third racesurface, the second race member defines a fourth race surface, and thethird race surface and the fourth race surface define a second racewaytherebetween. A plurality of rolling elements are disposed in the secondraceway.

In a third aspect, the rolling-element clutch assembly of the inventionincludes a first race member, a second race member and a plurality ofrolling elements. The first race member defines a first race surfacehaving a first ratchet surface portion. The second race member defines asecond race surface having a second ratchet surface portion and thefirst race surface and the second race surface define a racewaytherebetween. The plurality of rolling elements are disposed in theraceway and provide rolling support between the first race member andthe second race member when the first race member moves in a firstdirection relative to the second race member. The plurality of rollingelements disposed in the raceway include pairs of rolling elements. Atleast one of the pairs of rolling elements cooperate to engage the firstand second ratchet surface portions when the first race member moves ina second direction relative to the second race member, thereby impedingrelative motion between the first race member and the second race memberand providing load transmission capability.

In a fourth aspect, the rolling-element clutch assembly of the inventionincludes a first race member, a second race member and a plurality ofrolling elements. The first race member defines a first race surfacehaving a first ratchet surface portion. The second race member defines asecond race surface having a second ratchet surface portion and thefirst race surface and the second race surface define a racewaytherebetween. The plurality of rolling elements are disposed in theraceway and provide rolling support between the first race member andthe second race member when the first race member moves in a firstdirection relative to the second race member. At least one of theplurality of rolling elements engage the first and second ratchetsurface portions when the first race member moves in a second directionrelative to the second race member, thereby impeding relative motionbetween the first race member and the second race member and providingload transmission capability. The first ratchet surface is adjustablycoupled to the first race member.

In a fifth aspect of the invention, a rolling-element clutch assemblyincludes a first race member, a second race member and a plurality ofrolling elements. The first race member defines a first race surfacehaving a first ratchet surface portion. The second race member defines asecond race surface having a second ratchet surface portion. The firstrace surface and the second race surface define a raceway therebetween.A plurality of rolling elements are disposed in the raceway. The rollingelements provide rolling support between the first race member and thesecond race member when the first race member moves in a first directionrelative to the second race member. At least one of the plurality ofrolling elements engages the first and second ratchet surface portionswhen the first race member moves in a second direction relative to thesecond race member. The engagement of the rolling element with the firstand second ratchet surfaces impedes relative motion between the firstrace member and the second race member, thereby providing loadtransmission capability. The first ratchet surface portion includes aplurality of inclines extending along the first ratchet surface portionin the first direction, each incline is embedded into the first ratchetsurface portion and has a profile adapted for engaging one of theplurality of rolling elements. A rolling element separator is providedthat allows the rolling elements to freely roll when the first racemember moves in a first direction relative to the second race member andto freely pivot into engagement with or disengagement from the ratchetsurfaces when the first race member moves in a second direction relativeto the second race member.

In a sixth aspect of the invention, a rolling-element clutch assemblyincludes a first race member, a second race member and a plurality ofrolling elements. The first race member defines a first race surface.The second race member defines a second race surface and the first andsecond race surfaces defining a raceway therebetween. There are providedfirst and second ratchet portions. The plurality of rolling elements aredisposed in the raceway and provide rolling support between the firstrace member and the second race member when the first race member movesin a first direction relative to the second race member. At least one ofthe plurality of rolling elements engages the first and second ratchetportions when the first race member moves in a second direction relativeto the second race member. The first ratchet portion is adapted to moverelative to the first race member when at least one of the plurality ofrolling elements engages the first and second ratchet portions, therebypermitting controlled slippage of the clutch assembly.

In a seventh aspect of the invention, a rolling-element clutch assemblyfor use with a bearing assembly is provided. The bearing assembly hasfirst and second races and a plurality of rolling elements. The clutchassembly includes first and second adapter members and an adjustablelocking member. The second adapter member has a first ratchet extensionprojecting between the first and second races of the bearing assembly.The adjustable locking member has a second ratchet extension projectingbetween the first and second races of the bearing assembly opposite thefirst ratchet extension. Each of the first and second ratchet extensionshas at least one concavity for accommodating at least one of theplurality of rolling elements of the bearing assembly. The adjustablelocking member is adjustably coupled to the first adapter member suchthat in a first position the concavities of the first and second ratchetextensions are distanced from the rolling elements, thereby allowing therolling elements to freely roll. In a second position the concavities ofthe first and second ratchet extensions engage at least one of theplurality of rolling elements, thereby impeding relative motion betweenthe first and second race members of the bearing assembly. Theadjustable locking element is in the second position when the firstadapter member moves in a second direction relative to the secondadapter member.

In an eighth aspect of the invention, the rolling-element clutchassembly includes first and second race members and a plurality ofrolling elements. The first race member defines a first race surface anda first concavity. The second race member defines a second race surfaceand a second concavity. The first race surface and the second racesurface define a raceway therebetween, the raceway having a firstlongitudinal axis. The first concavity and the second concavity, whenaligned, define a passageway therebetween, the passageway foraccommodating a rolling element. The plurality of rolling elements isdisposed in the raceway, the rolling elements providing rolling supportbetween the first race member and the second race member when the firstrace member moves in a first direction relative to the second racemember. At least one of the plurality of rolling elements is capable oflodging in the passageway when the first race member moves in a seconddirection relative to the second race member, thereby impeding relativemotion between the first race member and the second race member andproviding load transmission capability.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of theinvention and together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a cross-sectional top view of a rolling-element clutchassembly of a type to which the present invention is applicable.

FIGS. 2a and 2 b are partial cross-sectional side views of therolling-element clutch assembly of FIG. 1 showing, in a break-away, asingle modified ball bearing in the free and locked positionsrespectively.

FIGS. 3a and 3 b are radial cross-sectional views of the rolling-elementclutch assembly of FIG. 1, taken along the line 3—3 of FIG. 1, in thefree and locked positions respectively.

FIG. 4a is a cross-sectional view of a first embodiment of the presentinvention in a free position.

FIGS. 4b and 4 c are partial top and cross-sectional side views,respectively, of a first race surface configuration of the firstembodiment.

FIGS. 4d and 4 e are partial top and cross-sectional side views,respectively, of a second race surface configuration of the firstembodiment.

FIGS. 4f and 4 g are partial top and cross-sectional side views,respectively, of a third race surface configuration of the firstembodiment.

FIG. 4h is a radial cross-sectional view of a modification to the firstembodiment of the rolling-element clutch assembly.

FIG. 4i is a perspective view of the first race member illustrating amodification to the raceway of the first embodiment.

FIG. 5 is a cross-sectional view of a second embodiment of the presentinvention in a free position.

FIG. 6a is a cross-sectional view of a third embodiment of the presentinvention in a free position.

FIG. 6b is a circumferential cross-sectional view of a section of thethird embodiment of the present invention in a locked position.

FIGS. 7a, 7 b, 7 c, 7 d, and 7 e are partial radial cross-sectionalviews of the first embodiment showing various raceway configurations.

FIGS. 8a, 8 b, 8 c, 8 d, and 8 e are radial cross-sectional views of thefirst embodiment showing various rolling element configurations.

FIGS. 9a and 9 b are radial cross-sectional views of a fourth embodimentof the present invention in a free and locked position, respectively.

FIG. 10a is a radial cross-sectional view of a fifth embodiment of thepresent invention, this embodiment illustrating the use of a rollingelement separator.

FIG. 10b is a perspective view of the rolling element separator of FIG.10a.

FIG. 11a is a radial cross-sectional view of a sixth embodiment of thepresent invention, this embodiment illustrating the use of a rollingelement separator.

FIG. 11b is a perspective view of the rolling element separator of FIG.11a.

FIG. 12a is a radial cross-sectional view of a seventh embodiment of thepresent invention, this embodiment illustrating the use of a rollingelement separator.

FIGS. 12b and 12 c are top and side views, respectively, of the rollingelement separator of FIG. 12a with rolling elements in place.

FIG. 12d is a cross-sectional view of the rolling element separator ofFIG. 12b, taken along the line 12 d—12 d.

FIG. 13a is a radial cross-sectional view of an eighth embodiment of thepresent invention, this embodiment illustrating the use of a rollingelement separator.

FIG. 13b is a side view of the rolling element separator of FIG. 13awith rolling elements in place.

FIG. 14a is a radial cross-sectional view of a ninth embodiment of thepresent invention, this embodiment illustrating the use of a rollingelement separator.

FIGS. 14b and 14 c are side views of the rolling element separator ofFIG. 14a with rolling elements in place.

FIG. 15a is a radial cross-sectional view of a tenth embodiment of thepresent invention, this embodiment illustrating the use of a rollingelement separator.

FIG. 15b is a side view of the rolling element separator of FIG. 15awith rolling elements in place.

FIG. 16a is a radial cross-sectional view of an eleventh embodiment ofthe present invention, this embodiment illustrating the use of a rollingelement separator.

FIG. 16b is a side view of the rolling element separator of FIG. 16awith rolling elements in place.

FIG. 17 is a radial cross-sectional view of a twelfth embodiment of thepresent invention, this embodiment illustrating the use of adjustableratchet plates.

FIG. 18 is a diametrical cross-sectional view of a thirteenth embodimentof the present invention, this embodiment illustrating the use of afloating ratchet ring.

FIGS. 19a-19 c are radial cross-sectional view of the first embodimentshowing various seal configurations.

FIG. 20a is a radial cross-sectional view of a fourteenth embodiment ofthe present invention in the free position, this embodiment illustratingthe use of spherical rolling elements.

FIG. 20b is a cross-sectional side view of the first race member andannular ring of FIG. 20a.

FIG. 20c is a radial cross-sectional view of the embodiment of FIG. 20ain the locked position.

FIG. 20d is a cross-sectional side view of the first race member andannular ring of FIG. 20c, with teflon tubes not shown for clarity.

FIG. 21a is a radial cross-sectional view of a fifteenth embodiment ofthe present invention, this embodiment illustrating the use of sphericalrolling elements and spring-loaded pawls.

FIGS. 21b and 21 c are cross-sectional side views of the embodiment ofFIG. 21a in a free mode and locked position, respectively.

FIG. 21d is a view taken along the line 21 d—21 d of FIG. 21b.

FIG. 21e is a view taken along the line 21 e—21 e of FIG. 21c of a ballbearing and pawls in a locked position.

FIGS. 22a and 22 b are a radial cross-sectional view and a view takenalong the line 22 b—22 b of FIG. 22a, respectively, of a sixteenthembodiment of the present invention in a free mode, this embodimentillustrating the use of spherical rolling elements and angledconcavities.

FIGS. 22c and 22 d are a radial cross-sectional view and a view takenalong the line 22 d—22 d of FIG. 22c, respectively, of the embodiment ofFIG. 22a in a locked position.

FIGS. 22e and 22 f are radial cross-sectional views of a modification tothe embodiment of FIG. 22a in the free mode and locked position,respectively.

FIGS. 23a and 23 b are a radial cross-sectional view and a view takenalong the line 23 b—23 b of FIG. 23a, respectively, of a seventeenthembodiment of the present invention in the free mode, this embodimentillustrating the use of a linking rolling element separator.

FIGS. 24a and 24 b are radial cross-sectional views of an eighteenthembodiment of the present invention in a free mode, this embodimentillustrating split race members.

FIGS. 25a and 25 b are a top view with the ratchet plate removed and aradial cross-sectional view of a nineteenth embodiment of the presentinvention in a free mode, this embodiment illustrating the rollingelement fill notch.

FIG. 26 is a radial cross-sectional view of a twentieth embodiment ofthe present invention in a free mode.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferred exemplaryembodiments of the invention, which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

A clutch is a device that will drive a load in one direction, but willallow it to move freely in the other direction. For instance, afreewheel clutch is a device that will drive a rotating load in onedirection, but will allow it to freewheel or spin at any speed in theother direction. This invention involves the use of rolling elements andspecial first and second race members to achieve both a rolling supportand a one-way clutch. This invention can accommodate both linear motionsand linear loads and rotational motions and rotational loads or torques.

FIGS. 1 through 3b, which show a rolling-element clutch such asdescribed in co-owned U.S. Pat. No. 5,573,094, generally illustrate thebasic elements and the arrangement of these elements of the presentinvention. FIG. 1 is a cross-sectional plan view of rolling-elementclutch 14. Clutch 14 has a first race member 16 defining a first racesurface, a second race member 18 defining a second race surface, and aplurality of rolling elements 10, or in this instance, ball bearings 10′in a raceway 20 therebetween. The ball bearings 10′ are modified byhaving their poles ground flat. The first race member 16 and the secondrace member 18 each have a ratchet surface 22. In this embodiment, theratchet surface 22 is generally perpendicular to the raceway 20. As bestshown in FIGS. 2a and 2 b, the ratchet surface 22 includes a series ofsawtooth inclines 24 embedded into the ratchet surfaces 22 of the firstand second race members 16, 18. As best shown in FIG. 1, each individualincline has a semi-circular profile 23 or cross-section, whichcomplements the circular shape of the ball bearings 10′.

The flattened poles 12 of the modified balls 10′ act as pawls. When thefirst and second race members 16, 18 rotate in the free mode, (FIGS. 2aand 3 a), the modified balls 10′ are forced to roll past the ratchetsurfaces 22. When the race members 16, 18 rotate in the engaged orlocked mode (FIGS. 2b and 3 b), the modified balls 10′ which willnaturally wobble slightly, will twist just enough to engage the ratchetsurfaces 22 of both race members 16, 18 and therefore the races willlock together. Torque is transmitted by the ratchet surfaces 22. Asshown in FIG. 2b, torque is transmitted when the modified balls 10′become wedged between the radially oriented sawtooth inclines 24 of theratchet surfaces 22 of the first and second race members 16, 18.

In operation, the first race member 16 may be connected to a drivenmember (not shown) and the second race member 18 may be connected to adriving member (not shown) or vice versa. The clutch 14 transmits torquein only one direction of rotation, as shown by the direction of thearrows in FIG. 2b and freely moves in the other direction, as shown bythe direction of the arrows in FIG. 2a. The modified balls 10′ move outof or into engagement with the sawtooth inclines 24 into adisengaged/free position or engaged/locked position, as shown in FIGS.2a, 3 a and 2 b, 3 b, respectively.

The ratchet surface 24 with its sawtooth inclines 22 need not be atright angles to the raceways 20. The driving member could be either racemember. The rolling-element clutch 14 can be machined into the mechanismthat uses its functions, making an even more compact assembly. Forexample, the first race member 16 may be part of a shaft and the secondrace member 18 may be machined into a housing. The number of balls 10and the number of ratchets 22 on each race member 16, 18 can all bevaried to increase the number of possible engagements. This woulddecrease the minimum backlash angle. The number of rolling elements 10and ratchets 22 could conversely be optimized to increase the number ofsimultaneous engagements. This would maximize the torque carryingability.

FIG. 4a illustrates a first embodiment of the rolling-element clutchassembly of the present invention. This figure is a cross-sectionalview, similar to FIG. 3a, showing an alternative orientation of therolling elements 10, or, in this instance, modified balls 10′, withinthe raceway 20 defined between the first race member 16 and the secondrace member 18. FIG. 3a shows the modified balls 10′ oriented so thattheir flat surfaces are adjacent the sawtooth inclines 22. FIG. 4a showsthe modified balls 10′ at right angles to the original orientation shownin FIG. 3a. However, the modified balls 10′ could be oriented in anyangle. Changing the orientation of the balls 10′ increases designflexibility and improves the ability of the rolling-element clutchassembly to resist forces in the non-radial direction.

The ratchet surfaces 22 could be a machined or cast part of theirrespect raceways. Alternatively, the ratchet surfaces 22 could bedistinct elements that are permanently attachable, or separable andreattachable, to the raceways. Furthermore, although the ratchetsurfaces are shown in FIG. 1 as sawtooth inclines with each sawtoothincline having a semi-circular profile 23, the inclines 24 may haveother profiles 23, so long as the profiles 23 allow the rolling elements10 to slide past the first and second race members 16, 18 rotating inone direction and to engage the ratchet surfaces 22 of the first andsecond race members 16, 18 rotating in the opposite direction. FIGS.4b-4 g illustrate three different ratchet configurations. FIGS. 4b and 4c show the ratchet configuration of the first embodiment, wherein eachindividual sawtooth incline 24 has a semi-circular profile 23 thatcomplements the shape of the rolling elements 10. Having such acomplementary profile maximizes the load-carrying ability of the engagedclutch assembly 14. However, machining such ratchet surfaces 22 isexpensive and time consuming. FIGS. 4d and 4 e show an alternativeratchet configuration, wherein the profile 23 of each individualsawtooth incline 24 is composed of a flat surface. These profiles 23 donot complement the shapes of the rolling elements 10, however, machiningsuch flat ratchet surface profiles 23 is much less costly and lesstime-consuming than machining semi-circular profiles 23, and isparticularly appropriate when the clutch assembly 14 is not highlyloaded. FIGS. 4f and 4 g show a further alternative ratchetconfiguration, wherein the profile 23 of each individual sawtoothincline 24 is composed of more than one flat surface, in this instance,a chevron. The chevron profile is less costly to machine than thesemi-circular profile, while generally having a higher load-carryingcapacity than the profile having a single flat surface.

FIG. 4c also shows the angle A—A of the incline of the sawtooth inclines24. Angle A—A can be shallow for fast engagements, such as needed inrapidly reciprocating devices, or it can be steep to allow the clutchassembly 14 to develop its full load carrying capacity. Typically, angleA—A will range from about 3°-20°. Moreover, any of the above-describedratchet surfaces 22 could be somewhat conformal or intentionallyflexible. Such conformal ratchet surfaces could allow soft stops or softengagements, limited slip arrangements, etc.

FIG. 4h shows a modification to the first and second race members 16, 18wherein the ratchet surfaces 22 are reduced in height from the ratchetsurfaces 22 shown in FIGS. 3a and 3 b. The ratchet surfaces 22 need notprovide for full contact with the modified balls 10′, because most ofthe torque is transmitted by only a portion of the ratchet surface 22.Smaller first and second race members 16, 18 could save material,weight, and machining time, provide access for lubrication, provideclearance for rolling element separators, provide room for environmentalseals, and make assembly and inspection easier.

In the freely moving direction of rotation, the modified balls 10′ ofthe first embodiment could have a tendency to wobble, which couldincrease wear of the components of the clutch assembly 14. In thelocking direction of rotation, the modified balls 10′ could have atendency to wobble haphazardly, thereby compromising the time toengagement. Shallow, diagonal grooves can be added to the surface of theraceway 20 to encourage the modified balls 10′ to roll without wobblingexcessively in the freely moving mode, and to encourage the modifiedballs 10′ to wobble when the clutch is moved in the locking direction.

FIG. 4i illustrates this possible modification to the first and secondrace members 16, 18. Diagonal scratches or short shallow grooves 25 areprovided on the raceways 20. These grooves point toward the deep ends ofthe ratchet pockets or sawtooth inclines 24. In the freely moving mode,as the modified balls 10′ roll over these grooves 25, the balls 10′ willveer away from the ratchet pockets, preventing any tendency for resonantwobbling. Resonant wobbling causes the balls to chatter during highspeed rotation. Upon reversing direction and transitioning into thelocked position, the grooves 25 guide the modified balls 10′ into thenearest pocket, thereby producing a faster, more secure engagement. Thegrooves 25 may be on one or both raceways 20, or on both sides of eachraceway 20, and the raceway 20 may be of any suitable cross-sectionalshape. For any given application, the number and angle of the groovesmay be determined by a person skilled in the art. Furthermore, theclutch assembly 14 need not be rotational, but could also be used inlinear motion applications. Finally, the rolling element 10 need not bemodified balls 10′, but, as discussed below, could be other suitablyshaped rolling elements.

FIG. 5 shows another embodiment of the present invention. This figure isa cross-sectional view showing a matched, opposing pair of rollingelements 10 in their respective raceways 20. Again, the rolling elements10 are shown as modified balls 10′. Alternatively, either one of thesemodified balls 10′ could be a regular ball bearing. Furthermore, themodified balls 10′ could be oriented in the same direction or indirections different from one another. Moreover, the raceways 20 couldbe axially adjacent (as shown), radially adjacent, or at some slantedorientation to one another.

Concurrently with changing the orientation of the rolling elements 10,the location of the ratchet surfaces 22 or sawtooth inclines 24 on thefirst and second race members 16, 18 will be varied. As shown in FIGS.2a, 2 b and 3 a, 3 b, the sawtooth inclines 24 are located on thesurfaces of the first and second race members 16,18 such that a vectorperpendicular to the ratchet surface 22 is parallel to the rotationalaxis. As shown in FIGS. 4 and 5, the sawtooth inclines 24 are located onthe surfaces of the first and second race members 16,18 such that avector perpendicular to the ratchet surface 22 points in the radialdirection. In general, changing the orientation of the rolling elements10 means there should be a corresponding change in orientation of thesawtooth inclines 24.

FIGS. 6a and 6 b illustrate yet another alternate embodiment of thepresent invention. In this embodiment, the space between the second racemember 18 and the first race member 16 can accommodate two rollingelements 10. This double-width raceway 20′ allows side-by-side placementof the rolling elements 10. Such a dual rolling element arrangementprovides a radial, axial, and moment load capacity that approximatelydoubles the load capacity of a single-width raceway assembly. In thefree mode, as shown in FIG. 6a, the motion is similar to that describedabove. In the engaged or locked mode as shown in FIG. 6b, the dualrolling elements 10 cooperate to transmit the torque between the secondrace member 18 and the first race member 16.

For the above-described embodiments, the raceways 20 and first andsecond race members 16, 18 could be non-circular and/or non-rotary forapplications in devices such as machine ways, linear motor tracks,roller coaster rails, material handling conveyors, unidirectional ballor roller screws, etc. Furthermore, for such non-rotary applications,the rolling elements 10 could actually be non-rolling elements such assliders. Even further, the orientation of the modified balls 10′ couldbe such that the balls 10′ are encouraged to tumble during freely movingoperation of the clutch assembly 14 so that the flat surfaces of themodified balls 10′ are continually changing direction. This aspect couldbe useful in short throw switches, relays, and indexing drives.

Both the first and the second race members 16, 18 are provided withraceways 20 in which the rolling elements 10 travel. The presentinvention may incorporate any of a variety of alternative racewaycross-sections, including those shown in FIGS. 7a-7 e. FIG. 7a shows aconical raceway 20 a; FIG. 7b shows a flat-top raceway 20 b; FIG. 7cshows a circular raceway 20 c; FIG. 7d shows an arched raceway 20 d; andFIG. 7e shows a back, or reverse, arched raceway 20 e.

The present invention may incorporate any of a variety of rollingelement configurations. FIGS. 8a-8 e illustrate several exemplaryrolling elements. FIG. 8a shows a spool-type rolling element 10 a. Thespool-type rolling element 10 a has great strength and is commonly foundin spherical rod ends used in aircraft control surface linkages. FIG. 8bshows a double cone rolling element 10 b, which can handle heavy loadswhile operating for a long service life. FIG. 8c shows a bow tie rollingelement 10 c. The bow tie rolling element 10 c provides high axialstiffness and can carry heavy loads. FIG. 8d shows a tapered-typerolling element 10 d, which can carry axial loads extremely well and isoften found in a tilted alignment with the small end pointed inwardtowards the axis of rolling element rotation. FIG. 8e shows abarrel-type rolling element 10 e, which is also capable of carryingheavy loads. Note that the configuration of the raceway 20 and the shapeof the rolling elements, in general (except for FIGS. 7c, 8 a, 8 b and 8e), do not match exactly. This mismatch allows the rolling elements toskew slightly sideways when the rolling elements are engaged by theratchets in the locked position.

FIGS. 9a and 9 b illustrate another embodiment of the present invention.The space between the second race member 18 and the first race member 16can accommodate crossed rolling elements 10. Raceways 20 and 21 areprovided in an X-shaped configuration that allows adjacent, alternatingrolling elements 10 to be oriented perpendicular to one another. As withthe dual rolling element arrangement, such a crossed rolling elementarrangement provides a radial, axial, and moment load capacity thatapproximately doubles the load capacity of a single-width racewayassembly. In the free mode as shown in FIG. 9a, the motion is similar tothat described in U.S. Pat. No. 5,573,094. In the engaged or locked modeas shown in FIG. 9b, the crossed rolling elements 10 cooperate totransmit the torque between the second race member 18 and the first racemember 16.

In FIGS. 9a and 9 b, the crossed rolling elements 10 are shown orientedat a 45° angle to the axis of rotation of the clutch assembly 14.However, it is within the scope of the present invention to orient thecrossed rolling elements 10 at any orientation relative to the axis ofrotation. Furthermore, it is within the scope of the present inventionto orient the crossed rolling elements 10 at any orientation relative toeach other.

FIGS. 9a and 9 b depict the crossed rolling elements 10 as segments ofspheres or ball bearings with opposite poles flattened. Other rollingelement shapes, including barrel, needle, double cone, rod, or disk, mayalso be used. Furthermore, the crossed rolling elements need not have afixed axis of rotation. Nor need they rotate at all. Linear motion, asused in roller coasters, ball screws, roller screws and jack screwdevices may be accommodated by the crossed rolling elements of thisembodiment.

The illustrations of the above embodiments show the rolling elements ofthe present invention as being in direct contact with each other.However, each of the above described embodiments may also be used withrolling element separators. Rolling element separators, located in theraceway 20 defined by the first and second race members 16, 18, preventthe rolling elements from directly contacting each other. Moreover,rolling element separators allow the rolling elements to freely rollwhen the clutch assembly 14 is in the free mode and to freely pivot intoengagement with or disengagement from the ratchet surfaces of the firstand second race members 16, 18 when entering or exiting the lockedposition, respectively. Because rolling element separators prevent therolling elements from directly rubbing against one another, they reducethe friction in the clutch assembly and thereby promote both a longerlife of the rolling elements and an increased rotational speed.Furthermore, rolling element separators provide inherent reservoirs forlubricants within the raceways, thereby allowing for better dispersionof such lubricants. In addition, the use of rolling element separatorsmay simplify the assembly of the rolling elements within the raceways bypermitting preassembly of a rolling element/rolling element separatorsubassembly.

A further embodiment of the present invention, illustrating the use of arolling element separator, is shown in FIG. 10a. The particular rollingelement separator of the embodiment of FIG. 10a is a perforated coneseparator 30 as shown in FIG. 10b. This perforated cone separator 30 isa shallow, truncated, hollow cone having an array of circular cutoutsthrough which the rolling elements 10 project.

Another embodiment illustrating the use of a rolling element separatoris shown in FIGS. 11a and 11 b. As shown in FIG. 11b, thiscone-with-fingers separator 32 is best described as a perforated coneseparator with a missing rim or as on open-perforated cone separator.The rolling elements are located in the partially open, circular cutoutswith the fingers, i.e., the material between the cutouts, extendingbetween the rolling elements. Although shown in FIG. 11b as having amissing or open inner edge, the cone-with-fingers separator 32 couldalternatively have a missing or open outer edge. Both the perforatedcone separator 30 and the cone-with-fingers separator can be made, i.e.,machined, cast, molded, etc., from a variety of materials, includingnylon, teflon, oil-impregnated sintered bronze, or other metallic ornon-metallic sheet or bar stock.

Still another embodiment of the present invention depicting the use of arolling element separator is shown in FIGS. 12a-12 d. As best shown inFIGS. 12b-12 d, a fingerstock separator 34 includes an elongate bar,having a longitudinal axis, from which a plurality of elongateprojections, or fingers, project. These fingers are regularly-spacedalong the length of the bar and are perpendicularly coupled to the bar.Furthermore, the attachments of these fingers to the bar all lie in asingle attachment plane. The fingers, as best shown in FIG. 12d, may becurved or bent out of the plane of attachment. As best shown in FIGS.12b and 12 c, the elongate bar extends along the row of aligned rollingelements 10 with the fingers projecting between the rolling elements.Although, the fingers are shown as projecting between each rollingelement 10 and the adjacent rolling element 10, the fingers could alsoextend between adjacent pairs of rolling elements.

A still further embodiment having a rolling element separator is shownin FIGS. 13a and 13 b. The rolling element separator of this embodiment,ring separator 36, includes a plurality of distinct rings or shortcylindrical sections located between the adjacent rolling elements. Thelongitudinal axes of the rings or cylinders, i.e., the axes that areperpendicular to the radial plane of the rings, are aligned with the rowof aligned rolling elements 10. The fingerstock separator 34 and thering separator 36 could be made from a variety of materials, includingnylon, teflon, oil-impregnated sintered bronze, other metallic ornon-metallic sheet stock, or other metallic or non-metallic wire stock.

Yet still another embodiment illustrating the use of a rolling elementseparator is shown in FIGS. 14a-14 c. A wire separator 38 extends alongthe row of aligned rolling elements 10 with wire fingers projectingbetween adjacent rolling elements 10. This embodiment is similar to thefingerstock separator 34 except that the elongate bar and the fingers offingerstock separator 34 are, in the wire separator 38, made from asingle length of wire. The wire travels along the row of rollingelements 10 and, between adjacent rolling elements 10, is bent down andlooped back up to form the fingers projecting between the elements.

Even another embodiment illustrating a rolling element separator isshown in FIGS. 15a and 15 b. Adjacent rolling elements 10 can beseparated by a small ball separator 40. The balls of the small ballseparator 40 are interstitially nestled between the adjacent rollingelements 10. The balls of the small ball separator 40 are preferablymade from a material having a highly lubricative quality.

A further embodiment illustrating a rolling element separator is shownin FIGS. 16a and 16 b. A band separator 42 includes a thin elongate topband and a thin elongate bottom band. These bands each encircle oppositehemispheres of the rolling elements 10 and are coupled together betweenadjacent rolling elements 10. The top and bottom bands could be riveted(as shown in FIG. 16b), welded, or bonded together to effect thecoupling. The band separator 42 could be made from a variety ofmaterials, including nylon, teflon, oil-impregnated sintered bronze,other metallic or non-metallic sheet stock, or other metallic ornon-metallic wire stock.

FIG. 17 shows an embodiment of the present invention having adjustableratchet plates 50. These adjustable ratchet plates 50 transmit linear orrotational loads between the first race member 16 and the second racemember 18 when the clutch assembly 14 is in the locked position.Adjustability of the ratchet plates 50 could be used in a variable loadlimiting situation. Furthermore, the adjustment mechanism could becalibrated to provide an indication of the position of the ratchetplates 50 relative to the first and second race members 16, 18. In oneapplication, the adjustability of the ratchet plates 50 could be used tofine tune the clutch assembly 14 upon wear of the components. Thistuning could be accomplished by manual adjustment or through automaticcontrol devices. In another application, the ratchet plates 50 could beadjusted so that they audibly interfere with the rolling elements 10 inthe free mode, thereby providing a sound cue.

The ratchet plates 50 are shown as movable rings having an adjustmentscrew 52 for moving the ratchet plates 50 toward or away from the polesof the modified bearing 10′ relative to the first and second racemembers 16, 18. Alternatively, the ratchet plates 50 could be threaded,the first and second race members 16, 18 could have corresponding,mating threads, and the ratchet plates 50 could be adjusted by threadingthe ratchet plates 50 into or out of the mating threads of the racemembers 16, 18. Adjustability of the ratchet plates 50 could also beaccomplished with cams, pneumatics, hydraulics, levers, etc. Evenfurther, adjustability could be accomplished automatically as a functionof, for instance, the loads on the rolling members or the transmittedlinear or rotational loads. Finally, although FIG. 17 shows twoadjustment screws, it is within the scope of the present invention toprovide for the adjustment of only a single ratchet plate 50.

As illustrated in FIG. 17, the adjustable ratchet plates may be springloaded. Adjustment springs 54 are shown as compression springs locatedbetween the adjustment screws 54 and the ratchet plates 50. Thesesprings ensure that in an over-load situation, the ratchet plates 50 maymove outward from the rolling elements 10, thereby allowing the firstrace member 16 to move relative to the second race member 18 when theclutch assembly 14 is in the locked position. Allowing the ratchetplates 50 to move permits controlled slippage of the clutch assembly 14in the locked position. Furthermore, such movement may prevent damage tothe clutch assembly components when too much load is applied.

Not shown in FIG. 17 is the mechanism whereby the ratchet plates 50 arekept from moving with respect to the first and second race members 16,18. Possible mechanisms for keeping the ratchet plates 50 from rotating,include a keyway and key, the adjustment screw itself, square ratchetplates, or other such devices as are known to a person skilled in theart. It is within the scope of the present invention to use otherrolling element shapes, including barrel, needle, cone, or rod, withadjustable ratchet plates. Furthermore, the clutch assembly withadjustable ratchet plates could be used for both linear motion androtational motion applications.

A further embodiment of the present invention, as shown in FIG. 18,allows the use of the rolling-element clutch assembly as a limited-slipclutch. The ratchet surface 22 of the second race member 18 is rigidlyattached to the second race member 18. The first race member 16 includesa floating ratchet ring 26 having a projection peg 28. In the free mode,the floating ratchet ring 26 does not rotate; while in the locked upmode, the floating ratchet ring 26 does rotate. Peg 28, attached to thesurface of the first race member 16 opposite the ratchet surface 22 andextending away from the rolling element 10, is integrally coupled to thefloating ratchet ring 26. A corresponding projection peg 29 is attachedto the wall of the first race member 16. Peg 29 interferes with peg 28when the floating ratchet ring 26 rotates in the locked position,thereby stopping the rotation of the floating ratchet ring 26.

The amount of slip, or rotation of the floating ratchet ring 26, dependsupon the placement of the projection peg 29, which is attached to thefirst race member 16, relative to the location of the projection peg 28,which is attached to the floating ratchet ring 26. As shown in FIG. 18,peg 28 and peg 29 will lock up after the floating ratchet ring 26 hasrotated approximately 180°, at which time the clutch will engage and thefirst and second race members 16, 18 will become locked together. If thesecond race member 18 is also equipped with a similar floating ratchetring and peg arrangement, nearly two full turns, as a maximum, could beexpected prior to full lockup of the first and second race membersoccurs. Furthermore, multiple peg and ring combinations could give anynumber of rotations before lockup. Similarly, less than full rotationcould be achieved by multiple pegs on the same ring or multiple pegs onthe same race member. Additionally, a rotational spring (not shown)could be used to restore the floating ratchet ring 26 back to theinitial position, or to lessen the slip loads.

A limited-slip clutch could be useful to prevent machine damage, forsafety purposes, or for enabling desired operating characteristics. Theclutch assembly 14 would slip until an intentional, predetermined amountof rotation was achieved. Such a limited-slip clutch could be used, forinstance, to balance loads such as those developed while hoisting asingle item with two winches, to compensate for unsymmetrical tire wearor different rates of rotation during turns in a dual wheel drive, tosmooth transitions of material among multiple conveyor belts, or toallow catch-up for full traction in multi-locomotives.

FIGS. 19a-19 c illustrate various methods for retaining lubricant withinthe raceways 20 and for preventing particles and liquid contaminants,i.e., water etc., from entering the raceways 20 and therebycontaminating the rolling element surfaces. The portions of the firstand second race members 16, 18 wherein the ratchet surfaces 22 arelocated may provide seats for sealing elements. For instance, FIG. 19ashows two O-rings 60 located between the first race member 16 and thesecond race member 18. FIG. 19b shows two wiper seals 62, i.e., thin,flexible flanges, attached to one of the first and second race members16, 18 and elastically flexed against the other of the first and secondrace members 16, 18. These seals may be continuous or quasi-continuous.FIG. 19c shows shield seals 64, wherein the gap between the first andsecond race members 16, 18 is filled with a shield seal 64. Theorientation of the gap between the race members can be changed toaccount for the loading on the clutch assembly 14. Furthermore, theshield seal 64 may be tailored for the application of the clutchassembly by making it from low friction, high load capacity, high/lowtemperature, etc. materials.

The above embodiments describe rolling-element clutch assemblies thatinclude non-spherical rolling elements. However, as described below, thepresent invention can also operate with standard spherical ball bearings100 as the rolling elements 10. Modified balls 10′ require expensive andtime consuming high precision shaping and grinding. Furthermore, inoperation in the locked up mode, typically only a single modified ball10,′ or other specially shaped rolling element, would engage the ratchetsurfaces. Thus, the torque capability of the clutch assembly 14 of theabove-described embodiments is typically limited by the maximum loadcapability of the single engaged rolling element 10. In contrast, usingstandard ball bearings 100 eliminates the need for high precisionmachining, and generally, should allow all of the rolling elements tocarry the applied torque, thereby increasing the torque capability ofthe clutch assembly 14.

FIGS. 20a and 20 b illustrate an embodiment of the present invention,shown in the free mode, whereby the rolling elements are part of astandard ball bearing assembly 11. FIGS. 20c and 20 b illustrate thesame embodiment in the locked position. The standard ball bearingassembly 11, such as a New Hampshire Ball Bearing (NHBB)#SSRI-1458ZZSL,typically includes an inner race, an outer race and standard sphericalball bearings 100, and, in this instance, teflon tube ball bearingseparators. The clutch assembly includes a first adapter member, asecond adapter member, and an adjustable locking member. In theembodiment of FIGS. 20a and 20 b, the clutch assembly 14 includes ansecond adapter member 80, an first adapter member 82, and a threadedannular ring 84 as the adjustable locking member. The first and secondadapter members 82, 80 surround the standard ball bearing assembly 11.In the engaged or locked position, the threaded annular ring 84, inconjunction with the first adapter member 82, operates to grip the ballbearings 100 of the standard ball bearing assembly 11.

In the embodiment of FIGS. 20a-20 d, the second adapter member 80includes a first portion with an inwardly-sloping ramp 88 as its innercircumferential surface, a cylindrical second portion attached to thefirst portion, a cylindrical third portion attached to the secondportion and having multi-start screw threads 90 on its innercircumferential surface, and a disk-like fourth portion attached to thethird portion.

The first adapter member 82 includes an inner cylindrical portion and anouter cylindrical portion, both attached to a disk-like portion. Theouter cylindrical portion of the first adapter member 82 includes acylindrical ratchet extension 83 that a projects between the races ofthe bearing assembly. Further, the cylindrical ratchet extension 83includes a series of circumferentially spaced pits or concavities 92, asbest shown in FIGS. 20b and 20 d, the number and spacing of theconcavities 92 corresponding to the number and spacing of the ballbearings 100. Ramps 93 may be provided between the concavities 92 toassist the transition from the free mode to the full lock up position.

The threaded annular ring 84 includes an inner cylindrical portionattached to a disk-like portion. Similar to the outer cylindricalportion of the first adapter member 82, the inner cylindrical portion ofthe threaded annular ring 84 includes a cylindrical ratchet extension85. And, similar to the cylindrical ratchet extension 83 of the firstadapter member 82, the cylindrical ratchet extension 85 of the threadedannular ring 84 has a series of circumferentially spaced concavities 92,wherein the number and spacing of the concavities 92 correspond to thenumber and spacing of the ball bearings 100. The disk-like portion ofthe threaded annular ring 84 has multi-start screw threads 94 on itsouter circumferential surface. These threads 94 complement themulti-start screw threads 90 of the second adapter member 80.

In the free mode shown in FIGS. 20a and 20 b, the concavities 92 of thethreaded annular ring 84 are distanced from the concavities 92 of thefirst adapter member 82, such that the ball bearings 100 are free toroll. The second adapter member 80 may rotate in the freely movingdirection relative to the first adapter member 82. When the secondadapter member 80 is rotated in the opposite direction relative to thefirst adapter member 82, the threads 94 of the threaded annular ring 84engage the multi-start threads 90 of the second adapter member 80 andthe annular ring 84 travels axially towards the ball bearings 100. Theamount of axial motion of the annular ring 84, between a fully locked-upengagement and a free mode, is a maximum of one ball diameter. In thelocked position shown in FIGS. 20c and 20 d, the concavities 92 of theannular ring 84 and the concavities 92 of the first adapter member 82mate with either side of the ball bearings 100, thereby locking the ballbearings 100 in place. The associated dimensions of the ball bearings100 and of the concavities 92 are fully complementary so that the ballbearings 100 fully engage the concavities 92. Because the load appliedto the clutch assembly 14 is carried by all of the ball bearings 100,the non-annular portions of the first and second adapter members 82, 80may be of light construction and materials compared to the annular ring84.

The standard ball bearing assembly 11 is slip-fit into the clutchassembly 14. Thus, the ball bearing assembly floats within the clutchassembly 14 and only one annular ring 84 is necessary for effecting thelockup mode. If the standard ball bearing assembly 11 has different ballbearing separators from those shown, the concavities 92 and ramps 93 mayinclude an accommodating groove.

Several modifications to this basic embodiment may be preferred tomaximize the performance. For instance, as shown in FIGS. 20a-20 d,circumferential springs 86 between the standard ball bearing assembly 11and the first and second adapter members 82, 80 could encourage theannular ring 84 to move axially away from the ball bearings 100. Theannular ring 84 may be spring-loaded or coupled to the clutch assembly14 in such a manner that in an over-torque situation the annular rings84 could slip, thus limiting the torque transmitted by the clutchassembly 14. Additionally, the multi-start screw threads may be singlestart screw threads, cams or even ball and ramp mechanisms. Furthermore,the ball bearing assembly 11 need not be a standard, off-the-shelfbearing, but could be custom designed and manufactured. The rollingelements need not be spherical ball bearings, nor need they beseparated.

In this embodiment, no actual ratcheting takes place. Thus, if anaudible cue is needed for an indication of being in the free mode, or ifratcheting is desired for other reasons, a spring mechanism or axialtensioning device could be added. Alternatively, ratcheting behaviorcould be encouraged by shaping the annular ring 84 to elasticallysuspend the ramps. Additionally, the direction of free movement and lockup could be placed under the operator's control or under automaticcontrol via devices such as reversible slant ramps, reversible screwthreading, or other reversible mechanisms. Finally, it is within thescope of the present invention to use this embodiment for rotary,linear, and non-linear motions.

FIGS. 2aa-2ae illustrate another embodiment of the present inventionthat uses standard spherical ball bearings for the rolling elements. Asshown in FIGS. 21ab and 21ad, the first and second race members 16, 18include a plurality of spring-loaded pawls 70 for engaging the ballbearings 100. The pawls 70 may include small block-like elementspivotably coupled to the race members 16, 18, and located withinindividual cavities 72 circumferentially spaced along the raceways 20 ofthe race members 16, 18. The edges of the pawls 70 opposite the pivotsmay be shaped to complement the spherical surface of the ball bearings100. Springs 74 between the pawls 70 and the first or second racemembers 16, 18 bias the pawls 70 away from the cavities 72, therebycausing the pawls 70 to extend into the raceway 20.

In the free mode, as best shown in FIG. 21b, as the first and secondrace members 16, 18 move relative to the ball bearings 100, each pawl 70is pressed into its corresponding cavity 72, thereby compressing thespring 74. As the ball bearings 100 roll by, each pawl 70 is forced tolie flush, or approximately flush, with the first surface of the racemembers 16, 18. Furthermore, in the free mode, as the ball bearings 100slide past the pawls 70 clicking may be heard.

In the locked mode, as best shown in FIG. 21d, the edge of the pawl 70opposite the pivot extends into the raceway 20 and interferes with thepassage of the ball bearings 100. Depending upon the number and designof the pawls 70, very little backward rotation of the race members maybe necessary to fully engage the ball bearings 100 with the pawls 70.Furthermore, if the number of pawls 70 is a whole number multiple of thenumber of ball bearings 100, and if the ball bearings 100 are equallyspaced, all of the ball bearings 100 may be engaged in the lockedposition simultaneously. Simultaneous action of the pawls 70 may beensured by linking the pawls 70 together (not shown). As shown in FIG.21d, the pawls 70 pivot on axes that are perpendicular to the axes ofrotation of the first and second race members 16, 18, and therefore,movement of the pawls 70 should not be effected by centrifugal forces.

This embodiment could also function with rolling elements that arenon-spherically shaped, including, among others, cylindrical, needle,and tapered rolling elements. Furthermore, the pawls could be activatedby automatic or manual devices other than springs, and the direction ofengagement of the pawls could be under user control. As with theprevious embodiment, this embodiment need not be based on rotary motion,but could function with linear or freeform motion such as conveyors androller coasters.

FIGS. 22a-22 d illustrate yet another embodiment of the presentinvention that uses standard spherical ball bearings for the rollingelements. As best shown in FIGS. 22a and 22 b, both the first and thesecond race members 16, 18 include a plurality of angled concavities 76cut into the surface of the raceway 20 and located to the side of theraceway 20. When a concavity 76 from the first race member 16 isopposite a concavity 76 from the second race member 18, a passageway forthe ball bearing 100 is formed. This passageway is positioned at anacute angle from the axis of the raceway 20.

In the free mode, as shown in FIGS. 22a and 22 b, the ball bearings 100travel in the raceway 20 adjacent to the concavities 76. When the firstand second race members 16, 18 are rotated with respect to one anotherin the free direction, the ball bearings 100 glide past the angledconcavities 76, because these concavities 76 are acutely angled in thedirection opposite to the travel of the ball bearings 100. When the racemembers 16, 18 are rotated in the locked direction, the ball bearings100, not being theoretically perfectly spherical, may wobble slightly,thereby randomly following other paths if not constrained.Alternatively, a preload or slight interference fit would also encouragethe ball bearings 100 leave the raceway 20 and start to travel down aconcavity 76. When at least one ball bearing 100 starts to travel down aconcavity 76 on one race member, the other race member will quicklybecome aligned with the first race member, thus allowing the formationof a passageway formed by a pair of concavities 76. The ball bearing 100is captured by and within the passageway formed by the pair ofconcavities 76 between the first and second race members 16, 18, therebylocking the race members together.

If the number of angled passageways, formed by pairs of concavities 76,is a whole number multiple of the number of ball bearings 100, and ifthe ball bearings 100 are equally spaced, the ball bearings 100 may allbe engaged in the locked position simultaneously. This simultaneous lockup can be facilitated by organizing the ball bearings 100 with a ballretainer or separator.

A modification to the embodiment of FIGS. 22a-22 d is illustrated inFIGS. 22e and 22 f. The angled concavities 76 of the first race member16 are located on one side of the raceway 20 and the angled concavities76 of the second race member 18 are located on the opposite side of theraceway 20. A slight movement of the first race member 16 relative tothe second race member 18 in a direction perpendicular to the directionthat the ball bearings 100 travel, as shown in FIG. 22f, causes the racemembers to become locked. The advantage of this modification is that allof the ball bearings 100 would become locked simultaneously, therebyensuring maximum torque carrying capability of the clutch assembly 14.

As with the previous embodiment, this embodiment could function withrolling elements that are non-spherically shaped, including, amongothers, cylindrical, needle, and tapered rolling elements, and theclutch assembly itself need not be based on rotary motion, but couldfunction with linear or freeform motion such as conveyors and rollercoasters.

FIGS. 23a and 23 b illustrate still another embodiment of the presentinvention that ensures that all of the rolling elements 10 substantiallysimultaneously engage the ratchet surfaces 22 in the locked position,thus enabling the rolling-element clutch assembly 14 to transmit higherloads than if only one or a few of the rolling elements 10 are engaged.This substantially simultaneously engagement of the rolling elements 10is accomplished by a linking rolling element separator 102. Linkingrolling element separator 102 links the rolling elements 10 so that whenone rolling element 10 pivots upon engagement with the ratchet surfaces22 all of the rolling elements 10 pivot. In the present embodiment, thelinking rolling element separator 102 is shown as a series of separatorbands 104 encircling each modified ball bearing 10′, each separator band104 linked to its neighboring separator band 104 by a pair of linkingelements 106. The separator bands 104 encircle each modified ballbearing 10′ so as allow the modified ball bearing to freely roll. Asbest shown in FIG. 23a, the separator bands 104 encircle the surfaces ofthe rolling elements 10 that engage the ratchet surfaces 22, i.e., theflattened poles of the ball bearings 10′. Pairs of linking elements 106are attached on opposite sides of the separator bands 104. The first endof a linking element 106 is attached to a first separator band 104 andthe second end of the linking element 106 is attached to an adjacentseparator band 104. The ratchet surfaces 22 may be less than full heightratchet surfaces, as previously describe, to provide a channel in whichthe linking elements 106 may travel.

In the free mode, each modified ball bearing 10′ freely rolls within theseparator band 104 and the rolling element separator 102 with themodified ball bearings 10′ travels within the raceway 20. In thetransition between the free mode and the lock up position, a firstmodified ball bearing 10′ starts to pivot and engage the ratchetsurfaces 22. The pivoting of the first modified ball bearing 10′ causesthe separator band 104 encircling it to also start to pivot, therebycausing the other separator bands 104 which are all linked together bythe linking elements 106 and the other modified ball bearings 10′ withinthe other separator bands 104 to likewise pivot. In this manner,substantially simultaneous engagement of the rolling elements 10 withthe ratchet surfaces 22 is accomplished. Furthermore, the linkingrolling element separator 102 may be spring-loaded to encourageengagement during the transition from the free mode to the locked upposition. Also the links may be a continuous, circumferential bandrather than individual links. The springs could be carried around eachpivot attachment such that, when relaxed the springs tend to hold themodified balls at an angle to the direction of rotation. This wouldcause audible clicking. Alternatively, the separator and linking bandmight be made from a single piece, perhaps molded of a material havinghigh resilience and lubricative qualities, such that the engaged, fullypivoted positions are the as-made configuration.

In general, the linking rolling element separator 102 must be closelytoleranced. A close tolerance between the separator bands 104 and therolling elements 10 must be maintained, and the stack up of thetolerances of the linking elements 106 must be limited. Such toleranceswould typically be on the order of ±0.01 mm. The linking elements 106need not be paired on opposite sides of the separator bands 104. Otherconfigurations of the linking elements 106 include locating all of thelinking elements 106 on the same side of the separator bands 104 oralternating the linking elements 106 on either side of the separatorbands 104. The number of ratchet inclines must be a whole numbermultiple of the number of rolling elements 10 so that there is a ratchetincline available for each of the rolling elements 10 when the clutchassembly 14 is in the engaged or locked up position.

Several different methods for fabricating and assembling the embodimentsof the present invention are provided. FIGS. 24a and 24 b illustratesplit race members. As shown in FIG. 24a, for ease of fabrication andassembly, race member 16 could be manufactured in two race memberportions 16 a, 16 b, wherein the race surface of race member 16 isprovided by combining the race surfaces of race member portions 16 a and16 b. Similarly, race member 18 could be manufactured in two race memberportions 18 a, 18 b, wherein the race surface of race member 18 isprovided by combining the race surfaces of race member portions 18 a and18 b. Race member portions 16 a, 16 b, and race member portions 18 a, 18b, could be fastened together with screws or other suitable means. Forinstance the race member portions could be press fit, brazed, or bondedtogether or a conformal wrap, such as that made from a ductile metal,could be used to fasten the race member portions together.Alternatively, as shown in FIG. 24b, for concentric race members 16, 18,race member 16 could be manufactured as a single member and race member18 could be manufactured in two race member portions 18 c, 18 d havingcomplementary threads. To assemble race member 18, race member portion18 c would be threaded onto race member portion 18 d.

FIGS. 25a and 25 b illustrate the present invention with rolling elementfill notches or slots. In this embodiment, the race member 16 could bemanufactured in two race member portions 16 c, 16 d. Race member portion16 d could be a removable ratchet plate. A subassembly composed of therace member 18 and the race member portion 16 c would form a partiallyexposed raceway 20, wherein the rolling elements 10 would be retainedbetween the race members 18, 16 c. For ease of assembling the rollingelements 10 into the raceway 20, the rolling element fill notches 108may be provided on opposing faces of the race member 18 and the racemember portion 16 c. The rolling elements 10 could be inserted into theraceway 20, formed between the race member 18 and the race memberportion 16 c, through rolling element fill notches 108. The rollingelement fill notches 108 would typically complement the shape of therolling elements 10. As shown in FIG. 25a, rolling element fill notches108 may be circular arcs for complementing modified ball bearings. Therace member portion 16 d may then be fastened to the race member portion16 c using a screw or other suitable fastener. The rolling element fillnotches 108 could be filled or plugged, if necessary, to provide asmooth interior raceway surface for the rolling elements 10.

FIG. 26 illustrates the present invention with removable ratchet plates.In this embodiment, race members 16, 18 include race surface portions 16e, 18 e, respectively, and ratchet plate portions 16 f, 18 f,respectively. The ratchet plate portions 16 f, 18 f are removablefastened to race surface portions 16 e, 18 e, respectively, with screwsor other suitable fasteners.

The embodiments illustrated in FIGS. 24a-26 may be used in conjunctionwith many of the embodiments described above to simplify the fabricationand assembly of the present invention.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

What is claimed is:
 1. A rolling-element clutch assembly, comprising: afirst race member defining a first race surface having a first ratchetsurface portion; a second race member defining a second race surfacehaving a second ratchet surface portion, the first race surface and thesecond race surface defining a raceway therebetween; a plurality ofrolling elements disposed in the raceway, the rolling elements providingrolling support between the first race member and the second race memberwhen the first race member moves in a first direction relative to thesecond race member, and at least one of the plurality of rollingelements engaging the first and second ratchet surface portions when thefirst race member moves in a second direction relative to the secondrace member, thereby impeding relative motion between the first racemember and the second race member and providing load transmissioncapability; and the first ratchet surface being spring loaded and beingadjustably coupled to the first race member.
 2. The clutch assembly ofclaim 1, wherein the second ratchet surface is adjustably coupled to thesecond race member.
 3. The clutch assembly of claim 1, wherein the firstratchet surface portion includes a plurality of inclines extending alongthe first ratchet surface portion in the first direction, each inclineembedded into the first ratchet surface portion and having a profileadapted for engaging one of the plurality of rolling elements.
 4. Theclutch assembly of claim 1 wherein the second ratchet surface is springloaded.
 5. A rolling-element clutch assembly, comprising: a first racemember defining a first race surface having a first ratchet surfaceportion; a second race member defining a second race surface having asecond ratchet surface portion, the first race surface and the secondrace surface defining a raceway therebetween; a plurality of rollingelements disposed in the raceway, the rolling elements providing rollingsupport between the first race member and the second race member whenthe first race member moves in a first direction relative to the secondrace member, and at least one of the plurality of rolling elementsengaging the first and second ratchet surface portions when the firstrace member moves in a second direction relative to the second racemember, thereby impeding relative motion between the first race memberand the second race member and providing load transmission capability;the first ratchet surface being adjustably coupled to the first racemember; and the second ratchet surface being adjustably coupled to thesecond race member.
 6. The clutch assembly of claim 5 wherein the firstratchet surface portion includes a plurality of inclines extending alongthe first ratchet surface portion in the first direction, each inclineembedded into the first ratchet surface portion and having a profileadapted for engaging one of the plurality of rolling elements.
 7. Theclutch assembly of claim 5 wherein the first ratchet surface is springloaded.
 8. The clutch assembly of claim 7 wherein the second ratchetsurface is spring loaded.